Within the past few years, transforming growth factor-beta (TGF-β) was identified as a factor that stimulates osteoblasts in bone. The TGF-β molecules are dimers containing two identical polypeptide chains linked by disulfide bonds. Although TGF-β has been purified from several tissues and cell types, it is especially abundant in bones. TGF-β is postulated to be one of the local mediators of bone generation and resorption, because of its presence in large amounts in bone and cartilage, because cells with osteoblast and chondrocyte lineage increase replication after exposure to TGF-β, and because TGF-β regulates differentiation of skeletal precursor cells. However, clinical studies using TGF-β as a therapeutic agent have been hampered by its limited availability. TGF-β1, for example, is usually purified from either human platelets, bone or soft tissues such as placenta and kidney. It is estimated that approximately one ton of bone is required to purify enough TGF-β1 for a single therapeutic treatment. While small amounts of TGF-β1 have been isolated as a recombinant protein which was processed and secreted by transfected mammalian cells into conditioned growth medium, the small amounts obtained and the high cost of production do not make this method of production commercially viable.
Bone morphogenetic protein (BMP) is a member of the transforming growth factor (TGF-β) family (Wozney, J. M. et al, Science, 242, 1528 (1988)), and its active form exists as a homodimer having a molecular weight of about 18 kilodaltons (kD). BMP has the function of acting on undifferentiated mesenchymal cells, inducing differentiation to chondroblasts and osteoblasts and effecting chondrogenesis and osteogenesis (Wang, E. A. et al. Proc. Natl. Acad. Sci. USA, 87, 2220 (1990)).
Although the BMPs are potent stimulators of bone formation in vitro and in vivo, there are disadvantages to their use as therapeutic agents to enhance bone healing. BMP's are relatively large, with a molecular weight of about 18 kD, and including between about 300 to 500 amino acid residues. Additionally, while human BMP is now produced using recombinant techniques, the cost of the protein remains high. Furthermore, receptors for the bone morphogenetic proteins have been identified in many tissues, and the BMPs themselves are expressed in a large variety of tissues in specific temporal and spatial patterns. This suggests that BMPs may have effects on many tissues in addition to bone, potentially limiting their usefulness as therapeutic agents when administered systemically. These disadvantages impose severe limitations to the development of BMPs as therapeutic agents.
U.S. Pat. No. 5,656,598, issued Aug. 12, 1997 to Dunstan et al., discloses therapeutic compositions for the prevention and treatment of pathological conditions involving bone and dental tissue. The Dunstan invention also provides a method to promote bone repair and/or growth for the treatment of pathological conditions involving bone tissue, for example, osteoporosis, Paget's disease, osteopetrosis, and periodontal disease and fracture repair, and healing of bone defects by administering FGF-1 to an animal or human in need of such treatment.
U.S. Pat. No. 6,258,778, issued Jul. 10, 2001 to Rodgers et al., discloses methods, kits, and compositions for enhancing bone, cartilage and cartilage repair, bone and prosthesis implantation, and attachment and fixation of cartilage and cartilage to bone or other tissues, and chondrocyte proliferation, comprising the administration of an effective amount of angiotensinogen, angiotensin I (AI), AI analogues, AI fragments and analogues thereof, angiotensin II (AII), AII analogues, AII fragments or analogues thereof, or AII AT2 type 2 receptor agonists.
U.S. Pat. No. 6,352,972, issued Mar. 5, 2002 to Nimni et al., discloses a bone morphogenetic fusion protein and a method of preparation of the bone morphogenetic fusion protein. The bone morphogenetic fusion protein comprises a purification tag and a bone morphogenetic active fragment. A method of preparing bone morphogenetic fusion protein comprises purifying and renaturing bone morphogenetic protein to provide an active bone morphogenetic fusion protein preparation. Methods of use of the bone morphogenetic fusion protein are also provided.
U.S. Pat. No. 5,750,651, issued May 12, 1998 to Oppermann et al., discloses 1) osteogenic devices comprising a matrix containing osteogenic protein and methods of inducing endochondral bone growth in mammals using the devices; 2) amino acid sequence data, amino acid composition, solubility properties, structural features, homologies and various other data characterizing osteogenic proteins, 3) methods of producing osteogenic proteins using recombinant DNA technology, and 4) osteogenically and chondrogenically active synthetic protein constructs.
U.S. Pat. No. 5,461,034, issued Oct. 24, 1995 to Rodan et al., discloses a biochemically pure polypeptide(s), termed osteogenic growth polypeptide (OGP), which exhibits stimulatory effects on osteoblastic cells, in vivo bone formation, and hemopoietic reconstruction.
Other related patents include U.S. Patent Publication No. 2002/0077281, published Jun. 20, 2002 (fracture healing using PTHRP analogs); U.S. Patent Publication No. 2002/0090671, published Jul. 11, 2002 (bone stimulating factor); U.S. Patent Publication No. 2002/0128202, published Sep. 12, 2002. (stimulation of bone growth with thrombin peptide derivatives); U.S. Pat. No. 4,086,221, issued Apr. 25, 1978 to Sakakibara et al. (polypeptides and process for producing the same); U.S. Pat. No. 4,167,557, issued Sep. 11, 1979 to G. Goldstein (ubiquitous immunopoietic polypeptide [UBIP] and methods); U.S. Pat. No. 4,959,455, issued Sep. 25, 1990 to Clark et al. (primate hematopoietic growth factors IL-3 and pharmaceutical compositions); U.S. Pat. No. 5,494,662, issued Feb. 27, 1966 to Kohji et al. (stimulator for bone formation); U.S. Pat. No. 5,663,146, issued Sep. 2, 1997 to C. Bowers (polypeptide analogues having growth hormone releasing activity); U.S. Pat. No. 5,681,818, issued Oct. 28, 1997 to Spencer et al. (therapeutic uses of human somatomedin carrier proteins); U.S. Pat. No. 5,698,521, issued Dec. 16, 1997 to McKernan et al. (native calcitonin mimetics); U.S. Pat. No. 5,698,672, issued Dec. 16, 1997 to Labroo et al. (synthetic calcitonin mimetics); U.S. Pat. No. 5,880,094, issued Mar. 9, 1999 to C. S. Tam (polypeptides that stimulate bone growth); U.S. Pat. No. 6,194,380, issued Feb. 27, 2001 to Kitamura et al. (agents for promoting bone formation); U.S. Pat. No. 6,228,984, issued May 8, 2001 to Hinuma et al. (polypeptides, their production and use); U.S. Pat. No. 6,291,428, issued Sep. 18, 2001 to Macaulay et al. (peptides which promote bone-forming cell attraction and adhesion); U.S. Pat. No. 6,300,127, issued Oct. 9, 2001 to Hair et al. (bone mineralization proteins, DNA, vectors, expression systems); U.S. Pat. No. 6,352,973, issued Mar. 5, 2002 to C. S. Tam (bone stimulating factor); EP Patent No. 128,041, published Oct. 26, 1995 (polypeptides exhibiting skeletal growth factor activity); International Patent No. WO 97/12036, published Apr. 3, 1997 (bone stimulating factor); U.S. Pat. No. 6,617,307, issued Sep. 9, 2003 to Nishimura et al. (peptide and osteogenetic accelerator); and International Patent No. WO 99/12561, published Mar. 18, 1999 (fracture healing using PTHrp analogs).
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. Thus a peptide for promoting healing of fractures solving the aforementioned problems is desired.